Mods...

[John H Farmer]

Hello All,

I'm new to the group, so this is to say hello.  I'm happily breathing life
into my  K1 #2822. It arrived for Xmas.  The build is going well and my
toroid winding skills are improving :)

I have a couple of questions about K1 mods:

About the ACG response time mod :  changing C31 to a lower value cap ( from
2.2uF to 1uF or lower) is mentioned most often,
but there is a  variation of opinion whether C67 should be lowered also.
Many of the postings about this are several years old.  I was just wondering
if ideas about this have evolved any further?  

Secondly, I've read on JL3AHK's site, about a mod to increase OP power of
the K1 to a consistent 7W across all bands.  He suggests adding a 0.001uF
cap in parallel with R30 on the RF board. I can't find any reference to this
mod anywhere in the archives.  Any opinions on this mod?

This K1 is my first Elecraft rig. I'm learning lots and having fun.  It's
practice for a K2.

Thanks from down here,

John
VK7JB


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[Don Wilhelm-4]

John,

On the AGC response, lowering C31 will decrease the delay time for the
AGC, and lowering C67 should increase the attack time.
I think the attack time is about right on the K1, and it is a matter of
choice whether you want to decrease the delay time.  This is audio
derived AGC, so while quite effective in protecting the ears it is never
as good as an AGC system that is derived at the IF (as in the K2).

I would recommend using the K1 with the stock values for a while to
determine if you want to make any changes.

Yes, a bypass capacitor on R30 will increase the gain of the driver, but
the driver transistor has recently been changed to a 2SC5739 which has
higher gain at higher frequencies than the 2SC2166, so this mod should
not be installed with the new transistor in place.  If you cannot get
adequate power out on all bands (greater than 5 watts with a 13.8 volt
power supply), look for the problem elsewhere.  Such a problem will
usually be found in the low pass filter.

73,
Don W3FPR

John H Farmer wrote:

> Hello All,
>
> I'm new to the group, so this is to say hello.  I'm happily breathing life
> into my  K1 #2822. It arrived for Xmas.  The build is going well and my
> toroid winding skills are improving :)
>
> I have a couple of questions about K1 mods:
>
> About the ACG response time mod :  changing C31 to a lower value cap ( from
> 2.2uF to 1uF or lower) is mentioned most often,
> but there is a  variation of opinion whether C67 should be lowered also.
> Many of the postings about this are several years old.  I was just wondering
> if ideas about this have evolved any further?  
>
> Secondly, I've read on JL3AHK's site, about a mod to increase OP power of
> the K1 to a consistent 7W across all bands.  He suggests adding a 0.001uF
> cap in parallel with R30 on the RF board. I can't find any reference to this
> mod anywhere in the archives.  Any opinions on this mod?
>
> This K1 is my first Elecraft rig. I'm learning lots and having fun.  It's
> practice for a K2.
>  
>

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